Where does this come from, and can I check it?

Spacecraft wait for the planets to line up along an elliptical path. The figure is taken from NASA Science, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a space fact?

Yes. It sits on the Space shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

What else can I read about it?

The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

Mars launch windows open about every 26 months

Spacecraft wait for the planets to line up along an elliptical path The cheapest route between two circular orbits is a Hohmann transfer, an ellipse that touches the inner orbit and the outer one. A Mars craft must arrive when the planet reaches the far end, so it launches when Earth sits about 44 degrees behind Mars in orbital phase. That alignment comes around roughly every 26 months. It sits in Mondo's space collection, one of 200 facts that each trace back to the reference below.

Where this comes from

NASA Science

Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.

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Space & Astronomy trivia

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Martian dust storms can swallow the whole planetOccasionally haze engulfs Mars for weeks and cuts off solar power Mars polar caps grow and shrink every yearFrozen carbon dioxide condenses out of the air, changing the planet's pressure Mars once had a global magnetic fieldRemanent magnetism in old crust shows it switched off billions of years ago A day on Mars lasts 24 hours 40 minutesRover teams work on Mars time and shift their day slightly each day Mars hosts the largest volcano in the solar systemOlympus Mons on Mars stands about two and a half times taller than Mount Everest Sunsets on Mars appear blue to the human eyeFine Martian dust scatters red light while allowing blue light to pass through

Tags: orbits, hohmann, mars

Mars launch windows open about every 26 months: the short answers

Where does this come from, and can I check it?: Spacecraft wait for the planets to line up along an elliptical path. The figure is taken from NASA Science, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a space fact?: Yes. It sits on the Space shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.